No batteries! Wireless tech recycles airborne radio waves

A world full of Internet-connected devices is a giant step closer to reality thanks to a new communications system that works without batteries or wires for power.

Just as we use mirrors to reflect light, or turbines to catch the wind, this technique — known as “ambient backscatter”— co-opts transmissions from TV and cellular towers and reflects them to exchange information between wireless devices. These waves serve as both a source of power and carriers of information.